1. Field of the Invention
The present invention relates to a signal reception apparatus for DS-CDMA cellular system having a sampling and holding circuit for holding analog input signal successively, a plurality of matched filters each for calculating a correlation between the input signal and a spreading code sequence and a plurality of calculation registers each corresponding to one of the matched filters for storing the spreading code sequence to be supplied to the corresponding matched filter.
2. Prior Art
The code division multiple access (CDMA) cellular system above is advantageous for an asynchronous system among base stations it is possible to identify the base stations and mobile stations and it is unnecessary to control the over a plurality of cells. The asynchronous system does not depend upon a time synchronization system, such as a global positioning system, so its base station can be established by a low cost. In the synchronous system, the base stations are identified according to the difference in time when signals from base stations reach to a mobile station. Since there are not defined any spreading codes for identifying the base stations, the base stations may be confused. While, the signal reception apparatus of the mobile station for asynchronous cellular system has a lot of performances, that is, a despread of a composite code of short and long codes, a fading compensation of a multi-path signal, a rake combining, the identification and evaluation of a plurality of base stations for an initial and peripheral cell search, changing of the transmission speed by variable spreading ratio and a multi-code communication for high speed communication. When a mobile station moves over a plurality of cells, base stations should be changed by soft-handover one after another.
Therefore, the signal reception apparatus for the CDMA cellular system may become complicated and large in circuit size. The signal reception apparatus is not preferable for a mobile station. If a long-delay path is to be processed, a plurality of matched filters are necessary in a traffic channel for one code sequence, so the circuit is further complicated. Also for the multi-code processing and soft-handover processing, a plurality of matched filters are necessary.
The present invention has an object to provide a signal reception apparatus for DS-CDMA cellular system of small size available for processing by a plurality of spreading code sequences.
According to the present invention, one or a plurality of matched filters are connected with a plurality of registers for storing a plurality of spreading code sequences through a multiplexer.